Hi, Guillermo Delgado From México City here
again. I am coming now with this new guide
about how this Analog to Digital process occurs
when we works over our interfaces and DAW´s.
Again sorry for not to present a video but my
english spoken is not as good and i want to avoid
misunderstand with bad pronunciations, so
here is my second week homework and as ever,
hope to be useful for everyone.
THANKS FRO READ!
It could be not too easy to
understand this process of how
audio signals come into an
interface and how a computer
can translate that signal to let a
DAW read correctly all that
information, but here i will try
to teach you in a simple way
how this process happens.
First we will define what Digital Audio means, we can define this
process as the codification of an analog audio signal into binary
information to let our computers and DAW´s read signals then
reconvert again to analog sounds for our ears to listen the original
signal again. This process is a chain of internal process which is
divided principally into three important steps: “Sampling”
“Quantization” and “Digital Coding”.
To understand how a computer represents sound,
consider how a film represents motion. A movie is
made by taking still photos in rapid sequence at a
constant rate, usually at twenty-four frames per
second. When the photos are displayed in
sequence at that same rate, it fools us into
thinking we are seeing continuous motion, even
though we are actually seeing twenty-four discrete
images per second. Digital recording of sound
works on the same principle. We take many
discrete samples of the sound wave’s
instantaneous amplitude, store that information,
and later reproduce those amplitudes at the same
rate to create the illusion of a continuous wave.
The samples contain information telling your computer
how the recorded signal sounded at certain instants in
time. The more samples used to represent the sound the
better the quality of the recorded sound. Sampling Rate is
the number of times per second that the measurements (or
sample) are taken. Typical rates between 15,000-52,000
samples per second.CD Sample Rate is 44.1 KHz. For every
second of sound you hear, 44,100 numbers are stored (or,
88,200 for stereo).44.1 KHz is standard for synths and
sampler keyboards. 48 KHz is now becoming the more
common standard. Sampling s based on Nyquist law.
Each sample of an audio signal must be described as
numerical value to be stored in the computer. The
numerical value expresses the instantaneous amplitude of
the signal at the moment it was sampled. The range of the
numbers must be sufficiently large in order to express
adequately the entire amplitude range of the sound being
sampled. Quantization error is unavoidable, but it can be
reduced to an acceptable level by using more bits to
represent each number. If we use two bytes (16 bits) per
sample, the quantization error will be only 1/65,356 of the
maximum signal amplitude. Since the quantization error
for each sample is usually random (sometimes a little too
high, sometimes a little too low), we generally hear the
effect of quantization error as white noise. This noise is not
present in the original signal; it is added into the digital
signal by the imprecise nature of quantization. This is
called quantization noise.
Samples are grouping in packets depending on
numbers of bits.
More numbers of bits Highest number of
Digital Coding is the last one of the processes that place
takes during Conversion A/D consists of the translation of
the analogical values of tension electrical that already have
been quantified (average) to binary System, by means of
pre-established codes . analogical Signal is going to be
transformed into digital Train of impulses (succession of
zero and ones).Parameters of Digital coding includes:
Number of ChannelsSampling RateResolution
(number of bits)Output Channels.
That´s all for now, any comment
or doubt please make it in my
post in forum.
Until next week, have a great